Polymer materials are utilized in an increasing number of categories of products, such as components for cars, boats, airplanes, within the electronics industry and other advanced industry as well as in paints and other coatings, for special packaging etc. The uses of polymer materials in new categories of products are only limited by the product properties. It is thus a continuous need for development of polymer products with improved properties e.g. with respect to increased scratch resistance, improved weather resistance, increased UV resistance, increased chemical resistance and improved properties with respect to antioxidation, anticorrosion etc.
In addition to pure polymer materials there has also been developed products based on materials that may be described as hybrids between inorganic and organic materials, which means that these materials are macro molecules that may have an inorganic core and organic branches.
Organic polymer molecules with branched structures have an enormous economical growth potential, particularly as components in new materials. So-called dendrimers are important examples of such polymer molecules with a perfectly branched structure as well as hyperbranched polymers with statistically progressive branching. Both dendrimers and hyperbranched polymers are denoted dendritic polymers. Dendritic (from Greec: “dendron”=tree) characterizes the principle of a progressive branching that is more or less perfect (G. R Newkome, C. N. Moorefield, F. Vögtle, “Dendrimers and Dendrons: Concepts. Syntheses. Applications”. Wiley-VCH, Weinheim, (2001)). Formula 1 illustrates the principle difference between linear polymers and dendritic polymers (hyperbranched polymers and dendrimers).

Dendritic polymers are particularly interesting because the T units may carry functional groups and the density of available functional groups per weight or volume unit of the polymer is much higher than what is the case for linear polymers. Functional T groups may be used to impart a function in a material, like an antioxidant, a UV absorber, or a radical scavenger as described in WO publication No. 02092668.
Alternatively the T groups may be used as very efficient cross-linkers of organic materials like epoxy resins or polyurethanes or as cross-linkers for thermoplastics. Due to the high degree of cross-linking between dendritic polymers and such organic compounds the dendritic polymers are superior cross-linkers compared to conventional cross-linkers like polyamines, polyalcohols, or multifunctional acrylates. Higher degree of cross-linking of an organic material like a cross-linked thermoplastic improves properties such as chemical resistance, weather resistance and wears resistance and makes the material useful for applications at higher temperature. (Hans Zweifel (ed.), Plastics Additives Handbook, Carl Hanser Verlag, München, (2001), 725-811). The T groups may also be used to organize the dendritic polymers in a network. As component in a material the dendritic polymer thus may induce improved barrier properties. Alternatively such dendritic polymers may be used as a binder or as a component in a thermoset plastic.
Dendrimers are usually manufactured in relatively complicated and expensive synthesis comprising several steps. The process conditions must be maintained very accurately in order to achieve a perfect progressive branch structure. Their industrial applications are therefore limited.
A general way of manufacture of hyper branched polymers was early described by Flory (P. J. Flory, Principles of Polymer Chemistry, Cornell University, (1953)). The polymerization of an AB2 monomer where A may react with B but where the reactions between A and A and between B and B are precluded, leads to a hyperbranched polymer.
Another way of manufacturing hyperbranched polymers involves the utilization of a reactive monomer that also carries an initiator, a so-called “inimer”. One example is the base catalyzed reaction between the inimer glycidol and the germ trimethylol propane as illustrated by Formula 2.

Hyperbranched polymers made in this way have properties that are quite similar to corresponding dendrimers (A. Sunder, R. Hanselmann, H. Frey, R. Mühlhaupt; Macromolecules, (1998), 32, 4240). This implies a much lower viscosity than that of linear polymers with a comparable number of free available HO-groups. A characteristic feature in the manufacturing process is that the inimer glycidol must be added very slowly to the germ and in a very thin dilution. Thus, the cost-efficiency of the process is severely reduced which is why the utility of hyperbranched polymers in industrial applications is quite limited.
It is previously known to perform certain modifications of the T groups of hyperbranched polymers. J.-P. Majoral, A.-M. Caminade and R. Kraemer, Anales de Quimica Int Ed., (1997), 93, 415-421 describe the functionalization of dendrimers containing phosphorus. The functionalization of the T groups can be made with identical/similar chemical groups or with different chemical groups.
FR 2761691 discusses dendrimers with functional groups at the surface that are modified through a reaction with cyclic thioesters. The reaction leads to a dendrimer surface with thiol groups that are attached to the dendrimer by amide or amine bondings. The products may be used as antioxidants. The dendrimers described are of the type polyamidoamine dendrimers (PAMAM dendrimers). PAMAM dendrimers contain tertiary amines that comparatively easy may be degraded after conversion to quaternary ammonium salts or aminoxides (A. W. Hofmann, Justus Liebigs Ann. Chem. (1851), 78, 253-286; A. C. Cope, E. R. Trumbull, Org. React. (1960), 11, 3 17-493; A. C. Cope, T. T. Foster, p. H. Towle, J. Am. Chem. Soc. (1949), 71, 3929-3935). Quaternary ammonium salts or aminoxides from amine based dendrimers can be formed when additives of amine based dendrimers are incorporated/compounded into thermoplastics with subsequent processing of the thermoplastics (e.g. film blowing, extrusion, casting). Such a degradation on one hand leads to a partial deterioration of the dendrimer core and on the other hand to formation of degradation products which may leak out and thereby reduce the surface quality of the polymer product. In addition tertiary amines may during processing of the thermoplastic form free radicals by decomposition of hydro peroxides (A. V. Tobolsky, R. B. Mesrobian, Organic Peroxides, (1954), Interscience Publishers, New York, p. 104-106). Dendrimers and hyperbranched polymers that contain tertiary amines thereby may induce an unintended degradation of thermoplastics during their processing, storage or use.
WO 01/48057 discusses multifunctional stabilizers against thermal oxidative degradation based on a core structure containing tertiary amines. As mentioned above this may lead to an unintended degradation of the core structure during processing, storage or use of (the) thermoplastics. The molar weight of a typical stabilizer manufactured in accordance with WO 01/48057 is 1246 g/mole.
WO 97/19987 discusses combinations of polymer additives and modified dendrimers that may be used in polymer materials. In the exemplification of WO 97/199987 the dendrimers are based on polypropyleneimine (PPI) of 3rd, 4th and 5th generation thereby including 16, 32, and 64 terminal amine groups. The core structure contains tertiary amines which may lead to an unintended degradation of the core structure during processing, storage or use of thermoplastics. The modification of the PPI dendrimer with a fatty acid to form a multifunctional fatty acid amide may bee conducted by means of heating in a suitable solvent. The tertiary amine groups in the core structure of the dendrimer and primary amine groups at the dendrimer surface may in presence of oxygen contribute to partial degradation of the dendrimer structure. As explained above free radicals may be formed by decomposition of hydro peroxides. Such a partial degradation is indicated by a faint brown or yellow colour of the modified PPI dendrimer, like in examples I, XI, and XII in WO 97/19987. Typical molecule weights for modified PPI dendrimers in WO 97/19987 are in the range 10 000 to 40 000 g/mole. In WO 02/092668 surface activated hyperbranched or dendritic stabilizers comprising at least one additive group and a hyperbranched or dendritic core is discussed. In the exemplification of WO 02/092668 only dendritic cores based on 2,2-bis-(hydroxymethyl)-propionic acid is used. The dendritic core and the bonding to the additive group thereby are mainly based on ester bondings, which make the stabilizer sensitive to hydrolysis. In addition the exemplification of WO 02/092668 shows that the molecules of the prepared stabilizers as determined by gel permeation chromatography is between 1000 and 1500 grams/mole.
One type of particulate polymers with properties corresponding to the properties of hyperbranched polymers comprises an inorganic SixO(1.5)x-core with one T group per Si atom and is known as POSS (polyhedral oligosilesquioxanes). The most common compound of this class is a POSS with x=8 and substantially cubic structure (C. Sanchez, G. J. de A. A. Soler-Illia, F. Ribot, T. Lalot, C. R. Mayer, V. Cabuil; Chem. Mater., (2001), 13, 3066). The manufacture of POSS is expensive (M. C. Gravel, C. Zhang, M. Dinderman, R. M. Laine; Appl. Organometal. Chem., (1999), 13, 329-336 and WO 01/10871) and their industrial applicability is therefore limited. Another type of particulate polymers with properties corresponding to the properties of hyperbranched polymers consists of an inorganic SixO(1.5)x core that carries one T group per Si atom and may be manufactured in a sol-gel process through controlled hydrolysis and condensation of a silane with a structure:X—B—Si(—Y)3 
Where Y is chosen among hydrolysable residues and X—B basically corresponds to the T group. The process is described e.g. in Applicant's own WO publication No. 0208343. Sol-gel processes may be cost efficient so that they may be conducted in industrial scale from favourable raw materials and under mild conditions, i.e. without use of high pressures or high temperatures and without particular precautions like extreme dilution or the like. Thus particulate polymers with properties corresponding to properties of hyperbranched polymers manufactured by sol gel processes are industrially applicable in many areas.
Many examples of utilization of sol gel products in polymer products are known (DE 199 33 098, EP 666 290). Normally the main focus is placed upon the inorganic SixO(1.5)x core with a size in the nanometer range and thereby upon the sol-gel product as inorganic nano particle, cf. DE 199 33 098 and EP 486 469. The inorganic residues X—B are typically used to anchor the sol gel products in an organic matrix, cf. EP 486 469. The sol gel process involving hydrolysis and condensation of a silane in which the X—B group contains one or more amide groups is particularly simple because no external catalyst is needed and because the process may be conducted at ambient temperature or under moderate heating. One example is controlled hydrolysis and condensation of γ-aminopropyl trialkoxysilane as described in applicant's own patent application, WO publication No. 0208343. Controlled hydrolysis and condensation of silanes in which the X—B groups contains one or more amide groups typically leads to a sol in which the resulting particulate polymer product has an organic/inorganic structure (hybrid polymer) that is comparable with a hyperbranched polymer product with a number of more or less free amine groups in the T groups. Such organic/inorganic hybrid polymers exhibits a large number of functional T groups compared to their weight and/or volume. At the same time its compact structure compared to the structure of linear polymers ensures desirable properties like low viscosity and good admixing properties with thermoset plastics and thermoplastics. An example of an organic/inorganic hybrid polymer with properties corresponding to a hyperbranched polymer is shown by Formula 3.

Organic/inorganic hybrid polymers with properties corresponding to properties of hyperbranched polymers find utilization e.g. as additives for polymer products like thermoset plastics and in lacquers and other types of coatings for surface protection. Used in appropriate amounts and with convenient particle size such hybrid polymers may contribute to a significant improvement of the properties of the plastic material or the lacquer in question, hereunder an increased wear resistance/scratch resistance and/or weather resistance.
Prior art technology in the area sol gel processes/products may broadly be divided in four main categories as elaborated in more detail below, with reference to some examples or publications.
A first category concerns modification of non-hydrolysed amine containing silanes (DE 2023968, WO 03/029361, EP 0253770, EP 666290), commonly with bi-functional epoxy compounds (like e.g. JP 2001192485), and use of same in thermoplastics or in coatings. Hydrolysis and condensation are in some cases subsequently conducted but prior to its addition to the thermoplastics or coating in question. In general this method leads to an undefined distribution of molecular sizes with many large molecules. This implies that a subsequent hydrolysis is difficult to conduct with great success, since water will not reach all sites of the very large molecules. A low degree of hydrolysis implies a lower scratch resistance and a lower weather resistance for the product. A further disadvantage is that the water used for the hydrolysis in presence of the organic parts of the molecule may react in an undesired manner with active groups of said organic parts. Utilization of non-hydrolysed alkoxysilane compounds in a thermoplastic or thermoset plastic material implies that alcohols like ethanol and methanol are formed during the subsequent, slow hydrolysis of the silane compound, i.e. subsequent to the plastic material having been exposed to water. This may lead to reduced mechanical properties of the thermoplastic or the coating. In addition the formation of alcohols such as ethanol and/or methanol may cause migration of additives and/or degradation products to the surface of a thermoplastic or a coating, which may reduce the surface quality severely.
Another category of prior art methods concerns modification of nitrogen containing sol gel products by chemical reactions in which amine groups are not directly involved (S. kar, P. Joly, M. Granier, O. Melnyk, J.-O. Durand, Eur. J. Org. Chem.; (2003), 4132-4139) or are not important (U.S. Pat. No. 5,744,243). The latter publication describes a coating composition that is achieved by mixing a) an acid catalysed hydrolysis and condensation of silane and monomer and b) a polymerized solution of organic polymer that contains functions which are compatible with the silane monomer. The coating is used for light reflection.
A third category concerns surface modification solely with SiO2 particles, i.e. particles of silica that may be, but need not be, manufactured by a sol gel process. A (non hydrolysed) silane is typically used for their modification, since the silanes form organic branches on the particles. This type of modification does not involve amine groups as reactive centres for the modification. Patent application No. 9603174-5 describes an aqueous dispersion of silica particles in different polymers used e.g. to increase the hardness.
WO publications Nos. 9407948 and 00/22039 describe this known technology where a surface modification of the oxide particles is conducted by silanization. In some cases the oxide particles may be made of hydrolysed silane. The silanes used for surface modification are not hydrolysed. These particles are used as filler and for the modification of polymers and foils. A disadvantage of products with such particles is that they cannot melt after being cured and their use as hyperbranched polymers is therefore limited. A disadvantage of this technology is that each silane has several functional groups that not necessarily bond to one and the same particle. If or when a silane is bonded to different particles, this contributes to an agglomeration of particles which is unfavourable. This may take place right away or occur over time, which means that the system is unstable. Due to the size of the silanes not many functions may be attached to each particles, which means that the degree of hyper branching is relatively low. In EP 0786499 is described a composition that may be cured in presence of moisture and comprising a) a multi functional acrylate, b) at least one alkoxy-functional organometallic component (TEOS) or hydrolysate, and c) at least one trialkoxyaminosilane.
A fourth category of prior art technology is sol gel processes that is based on hydrolysed silane and where a modification is made by means f an organic monomer, prepolymer or polymer.
EP 486 469 describes an inorganic/organic hybrid polymer that is prepared by polymerizing an organic monomer in presence of a partially or completely hydrolysed silane based sol. A typical example from EP 486 469 is the polymerization of methylmetakrylate in presence of a sol that is prepared by use of metakryloxypropyltrimethoxysilane. Use of the resulting composition is said to be as a wear resistant coating.
In U.S. Pat. No. 5,674,941 a coating composition is described which comprises hydrolysate/condensate of a) an epoxid containing silane, b) an organic amino functional silane, c a copolymer of two components selected from an acrylate monomer, an epoxy monomer, an organosilane and/or a terpolymer of said three components, d) a curing catalyst, e) a multifunctional acrylate, and f) a radical polymerization initiator. The composition is very complex and a chemical substitution of amine groups to form a polybranched, organic/inorganic hybrid polymer is not described.
U.S. Pat. No. 5,096,942 concerns a process in which firstly a polymer based on a hydrolysed silane, a so-called inorganic core, is prepared, which is bonded to a polymer chain like polystyrene. The hydrolysis of the silane is conducted in a way so that the condensation between Si—OH groups is actually prevented. The hydrolysed silane is thereafter added to a hydrolysed metal oxide or silane which results in a organic/inorganic hybrid polymer with properties corresponding to a hyperbranched polymer with a mole weight 1000-100 000 grams/mole. The silane does not contain nitrogen and no deliberate substitution of free amine groups in the sol is mentioned in U.S. Pat. No. 5,096,942.
U.S. Pat. No. 5,110,863 describes the manufacture of a sol that comprises an organosilane (with imidazole) and a metalalkoxide which is hydrolysed and can form an independent coating.
Objects
It is an object of the present invention to provide a method for the manufacture of components, materials, additives and/or material compositions based on particulate, polybranched organic/inorganic hybrid polymers.
It is a further object of the invention to provide methods as defined above in which the organic part may be varied by simple chemical substitutions.
It is a still further object of the invention to make such variation that at least one property of such components, materials, additives and/or material compositions is adjusted, such as but not limited to weather resistance, scratch resistance, barrier properties, dependent upon the actual area of utilization.
The Invention
The above mentioned objects are achieved by a method as defined in claim 1. According to another aspect the present invention concerns a method as defined by claim 2.
According to a further aspect the present invention concerns a particulate polybranched organic/inorganic hybrid polymer as defined by claim 21.
According to further aspects the invention concerns uses of products as manufactured by the methods defined above, as defined by the claims 25-29.
Preferred embodiments of the different aspects of the invention are disclosed by the dependent claims.
A skilled artisan will readily understand that claims 1 and 2 represent two aspects of the same invention and that the sole difference between the two relates to whether the organic amino-functional silanes used are hydrolysed and condensed or not hydrolysed. In the latter case hydrolysis and condensation form the first step in a process comprising at least two steps. In the fox inter case such a step obviously is redundant and therefore omitted. The skilled artisan will furthermore understand that the group X—B is chosen such that it will not be hydrolysed under the conditions that will be applied for the method.
In either case free amine groups are modified through a chemical substitution after the completed silane hydrolysis and condensation. Suitable chemical substitutions are conducted between the free amine groups in the T groups and reactive compounds that preferably react actually quantitatively with more or less free amine groups at temperatures typically below 470 K and pressures typically lower than 0.3 MPa.
Particularly interesting are sol-gel processes by which the T groups may be chemically modified in one or more steps immediately after the hydrolysis and condensation has been completed and for which the reactor equipment used for the silane hydrolysis and condensation may be employed. Such batch processes form the basis for a very cost efficient manufacture of particulate organic/inorganic polybranched polymers which can carry a large number of different T groups and which therefore may be used in a large number of different industrial areas of application.
By reactions typical for primary and secondary amines is meant addition reactions, substitution reactions and combinations of such reactions with suitable reactant such as, but not limited to, compounds comprising epoxy groups, isocyanate groups, reactive double bonds, substitutable groups, and proton donating groups.
By controlled hydrolysis and condensation is herein meant hydrolysis and condensation of a suitable silane compound:
The first step is hydrolysis of a suitable silane compound, R′—Si(OR)n, wherein the group R′ does not participate in the hydrolysis or condensation reactions. Alkoxide ligands are replaced by hydroxyl groups:Si—OR+H—OH Si—OH+ROH
A controlled amount of water and a controlled amount of a glycol based solvent is added during this step. The reaction temperature and the reaction time are also controlled.
The second step is condensation in which the hydroxyl group can react with hydroxyl groups or alkoxy groups from other silicon centres and form Si—O—Si bonds and water or alcohol respectively:Si—OH+HO—Si Si—O—Si+H2OorSi—OR+HO—Si Si—O—Si+ROH
To manufacture particles of a certain size it is required to establish chemical conditions that ensures a correct balance between the kinetics of the two reactions, namely condensation and hydrolysis. While the condensation contributes to formation of polymer chains from (single) monomer molecules, the hydrolysis contributes to a polycrystallinic precipitation or oxohydroxide precipitation. The combination of amino-functional silanes and exchange of alkoxide groups with strong ligands will moderate the hydrolysis reaction, which will ensure that the polymer chains not become too long but remain in the size of oligomers. In practice the particles will be prepared with a size of few nanometers, more typically less than 10 nm. A suitable stabilizer is normally added to the reaction composition to avoid oxidative degradation of reactants and reaction products during hydrolysis and condensation and subsequent modification. The resulting solution is comprised of inorganic polymer particles dipersed in a solvent.